1. Field of the Invention
The present invention relates to a method for surface modification by irradiating an insulator with an electron beam to modify the surface of the insulator.
2. Description of the Related Art
A method has been employed which subjects a work which must be processed to surface modification to modify a variety of physical and chemical characteristics including hardness, elasto-plasticity, electric conductivity, lubricity, durability, moisture resistance, corrosion resistance, wettability and gas permeability. As the foregoing method, a method (hereinafter called an "electron-beam applying method ") has been known with which a work which must be processed is irradiated with an electron beam to modify the surface of the work.
The electron-beam applying method is, as shown in FIG. 1, performed such that a work 101 which must be processed and which is secured to a holder 100 in a vacuum chamber is irradiated with an electron beam 103 emitted from an electron-beam source 102. The foregoing electron-beam applying method is not required to heat the work 101. Moreover, control of the energy of the electron beam which must be applied enables a variety of characteristics of the work 101 to be modified. Therefore, the electron-beam applying method has widely been used in an industrial field for manufacturing semiconductors.
The electron-beam applying method of the foregoing type, however, has been limited to a case in which the work 101 which must be processed is made of a material, such as metal, having conductivity. If the work 101 which must be processed is made of an insulator, such as plastic, the electron-beam applying method is limited to a case, for example, a polymerizing process, which does not require a process which must be completed in a short time. The reason for this lies in that employment of the electron-beam applying method in a case where the work 101 which must be processed is an insulator causes electric charges to be accumulated in the work 101 which must be processed. Thus, a so-called a "charged-up state " is realized. In the foregoing case, effective irradiation of the work 101 which must be processed with the electron beam cannot be performed. Hence it follows that the time to complete the process is elongated excessively when the electron-beam applying method is applied to the insulator. As a result, there arises a problem in that the productivity cannot easily be improved.
When the work 101 which must be processed is made of an insulator, such as glass, the conventional electron-beam applying method causes the glass work 101 to be heated owing to irradiation with the electron beam. As a result, conductivity is realized so that the charge-up state is neutralized. When the conventional electron-beam applying method is applied to the insulator, such as plastic, there arises a problem in that the work 101 which must be processed is melted or deformed owing to the heat generated by the electron beam.